Pipette

ABSTRACT

A pipette, comprising a plurality of side-by-side cylinders (1) with plungers (2) and seats (4) for attaching tip pieces to the pipette, and an operating member (5), to which the plungers are connected for moving them with the aid of an operating means (6) connectable to said operating member, said operating member (5) being fork-like and comprising a stem (7), a coupling member (8) connected to the stem and plunger rods (3) connected to the coupling member. The plungers are made of resilient material and are elastically connected to the plunger rods.

The present invention concerns e pipette comprising a body; mounted insaid body, a plurality of mutually parallel, side-by-side cylinders withplungers, plunger rods end seats for attaching tip pieces the pipette,end a fork-like operating member comprising a stem and a coupling memberthereto connected, the plunger rods with their plungers being connectedsaid coupling member in order to be simultaneously movable with the aidof an operating means that can be connected to the operating member, theoperating member with stem, coupling member and plunger rodsconstituting a solid entity, advantageously formed substantially in asingle work step, e.g. by extrusion

Regarding the state of art, reference is made to the Finnish Patents No.60137 and No. 73368. In these references pipettes of the type describedabove are disclosed, in which the plunger rods with plungers areconnected to a fork-like operating member for moving the plungerssimultaneously with the aid of an operating means connectable to theoperating member. However, problems have emerged in pipettes of kind,particularly as regards the mutually consistent movement of theplungers. The plungers tend to move inconsistently end even to seize inthe cylinders is due to manufacturing tolerances end to the even minorcentering errors in a plunger are likely to result in seizing, as theadjacent plunger(s) determine(s) the detection in which the couplingmember, and consequently the rest of the plunger rods and plungers,move.

The object of the present invention is to eliminate the drawbacks towhich attention was called in the foregoing.

It is a further object of the invention to provide a novel serialpipette which is less complex in design, more reliable in operation andmore advantageous to its manufacturing cost than any serial pipettes ofprior art.

Regarding the features characterizing the invention reference is made tothe claims section.

As set forth in the foregoing, the operating member has fork-resemblingshape. The coupling member connects with the stem substantially at rightangles, and the plunger rods connect with the coupling membersubstantially at right angles, parallelling the stem and disposed in arow, one beside the other. Therefore, the operating member is a solid,unitary entity which connects on one hand with the operating means ofthe pipette, e.g. a hydraulically or pneumatically operating powermeans, and on the other hand with the plungers of the pipette. By virtueof the design of said operating means, operation of the plungers of theserial pipette will be simultaneous and mutually consistent.

As taught by the invention, the plungers are made of resilient materialand they are elastically connected to the plunger rods.

In an embodiment of the invention the plungers are cylindrical in shape,and they have been arranged to abut with their outside surface againstthe inner surface of the cylinder. On their outside may be formed atleast one collar-like sealing ring, and each plunger, with sealing ring,has been shaped in a single work step of a single material, e.g. byextrusion moulding.

The cylinders are connected to the body advantageously at both ends andimmovably in their longitudinal, as well as advantageously theirlateral, direction.

Thanks to the invention the manufacturing of the pipette's operatingmember and plungers can be implemented in a simple, easy and inexpensivemanner. At the same time, simple and consistent operation of the pipetteis achieved, i.e., the emptying and filling of cylinders takes place ina constant and consistent, and reliable way. Further, thanks to theinvention, the pipette of the invention is advantageous as regardsmanufacturing cost.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in detail in the following, with the aid ofembodiment examples and referring to the attached drawing, wherein:

FIG. 1 presents a pipette according to the invention, opened and in topview,

FIG. 2 presents the pipette of FIG. 1, opened and in elevational view,and

FIG. 3 presents, in elevational view, the plunger of a pipette accordingto an embodiment of the invention.

In FIG. 1 is seen a pipette according to the invention, opened and intop view. The pipette comprises a box-like body 10 within which havebeen placed the cylinders 1 of the pipette, with plungers 2 and withseats 4 for attaching tip pieces (not depicted) to the pipette. Thepipette further comprises an operating member 5, to which the plungersare coupled for moving them with the aid of an operating means 6connectable to the operating member, such as a power cylinder.

The operating member 5 has fork-like shape. The operating membercomprises a stem 7, and to this stem is transversally connected a rigidcoupling member 8, to which the plunger rods 3 are connected. The stem 7is carried in the housing 10 to be movable longitudinally, in thedirection of the cylinders 1. The coupling member 8 connectssubstantially at right angles with the stem 7; similarly, the plungerrods 3 are connected substantially at right angles to the couplingmember 8. The cylinders 1 and seats 4 and the operating member 5, withstem 7 and coupling member 8 and with the plunger rods connected to thecoupling member, are mounted substantially in one plane so that when thestem of the operating member moves in the direction of the cylinders,the plungers 2 will move along with the stem of the operating member, bymediation of the coupling member, connected to the stem of the operatingmember, and of the rods. Thereby, the filling of all cylinders andindividual pipettes in a serial pipette will be effected simultaneously,and in mutually consistent manner.

In FIG. 1 is further seen a return spring 9, disposed to move the stem 5of the operating member, and thereby the coupling member 8 and plungerrods 3, and the plungers 2, away from the seats, that is, in the fillingdirection.

In the embodiment here depicted, the body 10 is mainly flat, and itconstitutes the housing for the pipette. Separate cylinders 1, withtubular liquid passages 12 parallelling them and constituting theirextensions, are provided with seats 4, which have been pushed in sleevefashion upon the tubular liquid passages. The cylinders together withthe seats have been mounted in mounting cut-outs provided in the body,so that the seats project through the apertures 13, the collars 14 ofthe seats abutting inwardly on the rims of the apertures, and thecylinders resting with their opposite ends on shoulders 15 formed by therims of apertures in the mounting frame 16 of the body, by radiallyoutward projecting flanges 17 formed on the respective ends of thecylinders. It is thus understood that all cylinders 1 with their seats 4are disposed in parallel, side by side and at constant spacing in thehousing constituted by the body 10, to be substantially immobilelongitudinally, and elastically in lateral direction.

In FIG. 3 is seen a plunger 2 conforming to an embodiment of theinvention. The plunger has been manufactured by extrusion of plastic rawmaterial, mainly in a single work step. The plunger 2 has mainlycylindrical shape includes a collar-like sealing ring 11 and has beenfitted into the cylinder.

The plunger 2 is advantageously made of resilient, elastic plasticmaterial. The plunger is connected to the plunger rod 3 e.g. by frictionbond, by gluing, with threads, or in any way whatsoever: the juncture isadvantageously laterally resilient so that plungers located side by sidecan become centered in the cylinders flexibly and without seizing.

The invention is not confined to the embodiment examples that have beenpresented: its embodiments may vary within the scope of the claimsfollowing below.

I claim:
 1. A serial pipette comprising: a main body, said main bodyincluding a plurality of plunger rods, a coupling member and a stem,said plunger rods, said coupling member and said stem are connected as asingle body, a plurality of cylinders corresponding to the number ofsaid plunger rods, said cylinders attached to said main body, and aplurality of plungers corresponding to the number of said plunger rods,said plungers at least partially within said cylinders in which:a) saidplungers are made of a resilient material; and b) said plungers areelastically connected to said plunger rods.
 2. The pipette of claim 1,wherein said plungers are cylindrical in shape, and that each of saidplungers has been formed in a single work step of a single materialwhich is more elastic than said single body.
 3. The pipette of claim 2,wherein said single work step includes extrusion.
 4. The pipette ofclaim 1, wherein said cylinders are connected to said main body suchthat they are substantially immobile in the longitudinal direction.